| Based on the structure of aldose reductase ?AR?, WJ-38, 2-[6-Methoxy-3-?2,3-dichlorophenyl?methyl-4-oxo-1 ?4H?-quinolinyl] acetic acid, was designed and synthesized by Shenyang Pharmaceutical University. WJ-38 exhibited strong AR inhibitory activities both in vitro and in vivo, so it might be used for the treatment of diabetic complications. In this paper, the inhibition of polyol pathway activity by WJ-38 was investigated, and pharmacokinetic and metabolic properties of WJ-38 were evaluated, which could offer the reference for its dosage form designation and clinical research.A simple and rapid HPLC-UV method using pre-column derivatization was developed to determine endogenous sorbitol in rat erythrocytes. It is observed that sorbitol accumulation in erythrocytes occurred in streptozocin-induced diabetic rats, indicating that polyol pathway was activated under hyperglycemic conditions. After 16 weeks of treatment with WJ-38 ?16.7, 50 and 150 mg-kg-1?, the sorbitol concentrations in erythrocytes of diabetic rats were markedly reduced than those of untreated ones. The inhibitory effect of WJ-38 on polyol accumulation was similar to epalrestat. The results showed that WJ-38 could effectively prevent diabetic complication by inhibiting the activity of polyol pathway.A fast and sensitive LC-MS/MS method was developed for the quantification of WJ-38 in rat plasma. The method was successfully applied to the pharmacokinetic study of WJ-38 in rats after intragastrical or intravenous administration of WJ-38. Following intragastrical administration of WJ-38 to rats at doses of 16.7, 50 and 150 mg-kg-1, plasma levels of WJ-38 reached maximum values of 854 ± 548, 1006 ± 403 and 2974 ± 1001 ng·mL-1 at 3.0 ± 0.7, 3.3 ± 1.1 and 3.2 ± 0.5 h,respectively. The AUC0-t were 3681 ± 1486,5919 ± 1360 and 13045 ± 6207 ng·h·mL-1,respectively,and the AUC0-? were 3953 ± 1614,6241 ± 1253 and 13278 ± 6280 ng·h·mL-1,respectively. The t1/2 were 3.0 ± 0.7,3.3 ± 1.1 and 3.2 ± 0.5 h, respectively. Linear pharmacokinetics of WJ-38 was observed in rats within the dose range studied. After intravenous administration at a dose of 50 mg·kg-1,the Cmax,AUC0-t,AUC0-?, t1/2 of WJ-38 were 503100 ±289807 ng·mL-1,208232 ± 85308 ng·h·mL-1, 208883 ± 84730 ng·h·mL-1 and 3.7 ± 1.5 h,respectively. The pharmacokinetic process of WJ-38 in rats was fitted to a two-compartment model,and the absolute bioavailability of WJ-38 was 3.5%.The tissue distribution of WJ-38 in rats was investigated. After intragastrical administration of WJ-38 at a dose of 50 mg·kg-1, the drug was quickly and extensively distributed. The highest concentrations of WJ-38 in most of tissues were observed at 0.5 h after administration. The concentrations of WJ-38 in heart, liver and kidney reached the highest levels at 1 h after administration. Besides small intestine and stomach, kidney and liver showed higher drug concentrations than other tissues. WJ-38 was detected in the brain, indicating that it could cross the blood-brain barrier. The concentrations of WJ-38 in various tissues were significantly reduced at 5 h after dosing. The tissue concentrations of WJ-38 declined to very low levels at 12 h after dosing,indicating that the elimination of WJ-38 from the tissues was rapid, and it did not easily accumulate in the tissues.The excretion of WJ-38 in rats was studied. After intragastrical administration of WJ-38 at a dose of 50 mg·kg-1,the cumulative amounts of the drug excreted in rat urine,feces ?0?96 h? and bile ?0?48 h? were 66.6 ± 12.9, 5226 ± 1339 and 612 ± 135 ?g, respectively. The urinary,fecal and biliary excretion amounted to 0.7, 52.3 and 6.1% of the dosage, respectively. The data suggested that WJ-38 was mainly excreted unchanged in feces.In vivo and in vitro metabolism of WJ-38 in rat were investigated by LC-MSn method. As a result, 8 metabolites were found in all, including 6 phase I metabolites and 2 phase ? metabolites.Hydroxylation, demethylation and conjugation with sulphuric acid after hydroxylation were the primate metabolic pathway of WJ-38 in rat. Hydroxylation and demethylation could be catalyzed by rat liver microsomes.The binding of WJ-38 to plasma proteins was determined by equilibrium dialysis with final concentrations of 1000, 2000,4000 ng·mL-1. The binding of WJ-38 to rat plasma proteins were 97.9 ± 0.4,98.2 ± 0.7 and 98.2 ± 0.2%, respectively. The binding of WJ-38 to human plasma proteins were 99.6 ± 0.1,99.6 ± 0.1 and 99.7 ± 0.1 %? respectively. WJ-38 was highly bound to plasma prteins ?> 97%?. There was no statistical difference among the plasma protein binding of WJ-3 8 at three concentration levels in each protein source,but significant difference was found between species. |
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